Fentanyl and clonidine as adjuncts to a mixture of local anesthetics in potentiating postoperative analgesia in supraclavicular block: A randomized controlled study

BACKGROUND: Brachial plexus block is popular for upper limb surgeries as it is effective for postoperative analgesia. AIMS: The aim of the study was to compare fentanyl and clonidine as adjuncts to a mixture of local anesthetics in potentiating postoperative analgesia in the supraclavicular block. MATERIALS AND METHODS: Sixty patients of the American Society of Anesthesiologist I and II undergoing upper limb surgeries lasting more than 30 min were included and randomly divided into two groups of 30 each. In clonidine (C) group, patients received 10 ml of 0.5% bupivacaine + 20 ml of 2% lignocaine with adrenaline (1:200,000) and 1 μg/kg clonidine diluted till 35 cc with normal saline. In fentanyl (F) group, patients received 10 ml of 0.5% bupivacaine + 20 ml of 2% lignocaine with adrenaline (1:200,000) and 1 μg/kg fentanyl diluted till 35 cc with normal saline. Patients were observed for onset and duration of sensory and motor blockade, duration of analgesia, postoperative pain, and adverse effects. RESULTS: The mean onset of sensory block was faster in Group F (8.43 ± 2.897 min) as compared to 13.17 ± 2.451 min in Group C. The difference between the two groups was statistically strongly significant (P < 0.0001). There was a significant reduction in the onset of motor block in Group F (14.67 ± 1.84 min) compared to (18.17 ± 2.45 min) Group C with P < 0.0001 (statistically strongly significant). There was a significant increase in the duration of analgesia in Group C (16.63 ± 2.04 h) compared to Group F (8.79 ± 1.50 h) with P < 0.0001. There was bradycardia (pulse did not fall below 60) in two patients of Group C (treated with atropine intravenous [i.v.]). Two patients of Group F complained of nausea and vomiting once in the early hours of surgery for which ondansetron i.v. was given. There were no significant side effects in either of the groups. CONCLUSION: Both clonidine and fentanyl establish a good safety profile. Fentanyl ensures a faster onset of sensory and motor blockade, while clonidine ensures a longer duration of sensory and motor blockade as well as prolonged analgesia.